[Diuretics in the treatment of hypertension. Efficacy, safety and tolerability].

In the treatment of hypertension, both the thiazide diuretics hydrochlorothiazide and bendroflumethiazide and the "thiazide-like" diuretics chlorthalidone and indapamide are used. Guidelines refer to these as the class of thiazide diuretics suggesting their interchangeability. However, bendroflumethiazide and hydrochlorothiazide, at least in the commonly used low dose range, are less potent with respect to blood pressure lowering and may also be less effective in preventing morbidity and mortality events. This is of great clinical relevance since hydrochlorothiazide is by far the most widely prescribed diuretic. Increasing the dose of hydrochlorothiazide would further reduce tolerability of treatment due to an increase in dose-dependent side effects. The underlying mechanisms of the suggested superiority of chlorthalidone on cardiovascular morbidity and mortality remain unclear. The half-life of chlorthalidone has been estimated at >50 h thus exceeding the half-life of hydrochlorothiazide by about 5-fold. Given the documented irregular intake of antihypertensive drugs, the prolonged efficacy of chlorthalidone makes this agent a "forgiving drug" with a definite advantage over hydrochlorothiazide. On the basis of the available evidence, whenever diuretic treatment is indicated in a hypertensive patient, a thiazide-like agent, preferably chlorthalidone should be employed.